A manipulator, in particular an endoscopic manipulator for medical or non-medical technical applications, comprises, for instance, gripping members on a proximal end that can be slid, rotated, or pivoted with respect to one another and, on a distal end, a manipulation device. The distal end is connected with the proximal end by a rigid or flexible shaft. If the gripping members on the proximal end are moved with respect to one another and/or a force or moment acts on the gripping members, this motion and/or this force or this moment is transmitted to the manipulation device. For this purpose a transmission element, which can move with respect to the shaft, is provided in the shaft of the manipulator. If the shaft is bent or bendable, then at least either the shaft or the transmission element must be flexible, at least in areas in which the bending varies, in order to make a relative mobility possible.
In patent EP 1 055 397 A1, a medical instrument for severing tissue in the human or animal body is described in which a spiral spring surrounds a rigid bent rod and is slid with respect to said rod in order to transmit a force from the gripping members on one end of the instrument to a tool on the other end of the instrument.
In patent EP 1 872 729 A1, a medical element for gripping an object is described. A force transmission element with a helical structure is positioned in a shaft between a grip and a distal section.
The helical force transmission element described in patent EP 1 872 729 A1 must be bendable and thus must comprise an elastic material, for instance plastic. Consequently, however, the force transmission element also comprises a high pliability, or compressibility and stretchability, in the longitudinal direction, in which it is to transmit a force. In addition, the force transmission element comprises a surface of some size that is internally contiguous with the shaft. The resulting sliding friction or static friction makes sensitive operation difficult and increases wear and tear. The weakening of the cross-section of the force transmission element between the coils and turns of its helical structure is desirable to increase the flexibility. At the same time, however, because of the stress concentration there, it is particularly easy for fissures or other damage to occur in the force transmission element that can lead to its failure.